An adjustable mount for anchoring a safety belt on a vertical surface of a motor vehicle typically has a vertically elongated guide rail fixed to the surface and having a front face turned away from the surface and a rear face turned toward the surface. The rail is formed with a longitudinally extending throughgoing slot and with a row of stops. A slider displaceable along the rail has a guide extending forward through the slot and formed with a forwardly open threaded bore receiving a bolt. A spring braced between one of the faces and the slider urges the slider into engagement with the stops and a buckle traversed by the belt is mounted on the bolt.
In this type of fitting the rail has stops cut into the longitudinal rail edge, the portions of the rail between the stops being bent back. The slider is as an elliptical-section tube formed by two welded-together pieces of sheet metal. This tube has a major axis greater than the width of the rail and a minor axis equal at least to the front-to-back thickness of the rail including that of the portions bent back between the stops.
The slider is formed with abutments complementary to the stops and is provided internally with a synthetic-resin bushing facilitating sliding movement along the rail. A leaf spring is braced between the rail and the slider to push it transversely such that the stops engage between the abutments and the slider and rail cannot move relative to each other longitudinally. Compression of this leaf spring allows the stops and abutments to be disengaged from each other and the slider can then be moved along the rail.
Such a piece of equipment is relatively complex and expensive to manufacture. In addition if the slider is accidentally pushed past the end of the row of stops, it will make accurate setting impossible and even allow the slider to slip when tension is exerted on the belt.